Our 2004 Boxster S 3.4 has on 3 occasions over the past couple of weeks acted up when starting from cold. It’s sluggish to fire up and when it does it runs roughly with the engine shuddering. The CEL comes on and the last time it behaved like this it flashed, so quite alarming

However, we dared to try again after switching off and it fired up perfectly well, sounds as sweet as ever and subsequently drives as well as ever too. It’s only done this at cold start up and does live outside so it is quite cold and damp.

After it did it again yesterday I took it to my friends workshop. His PIWIS told us it had misfired (on cyclinders 1,4,6) but there were no other faults such as sensors or coils, which along with plugs were all renewed a few months ago at its major service in any case. Thought about dodgy tank of petrol but it did this before and after it was filled it up.

All fault codes were cleared and I filled it up again just in case on the drive home, during which I gave it a spirited burst and it was good as gold. It also started and ran fine for my wife this morning, so we’ll to run and observe.

When it does it again we’ll get it back on the PIWIS and take a closer look, in the meantime if anybody has any ideas and/or has had something similiar it would be great to know _________________991.1 C2, 986 Boxster S
Past pleasures: 997.1 GT3, 997.2 C4S Cab, 993 C2, 997.1 C2S, 996.1 C4

ragpickerEstoril

Joined: 14 Apr 2013Posts: 3913Location: North East England

Posted: Sun Nov 18, 2018 3:53 pm Post subject:

Interesting fault MJA911. It might be worth running some injector cleaner through a couple of tanks of fuel in case the injectors are a bit clogged up

If it clears with the cycling of the ignition I would be suspicious of something electric

It could also be clogged injectors too when thinking along those lines...?

@MJA911, I've always used Redex. Wait until you've got about 30 miles left in the tank and then pour half of it in. Then run it until nearly empty and fill up with the usual stuff. You don't want to dilute it too much in the fuel otherwise you'll lose what effect it does have.

Thanks demort. Yes it had new coils (and plugs) in the summer and has been sweet as a nut until now.

Thanks for the tip on the solenoid and fuel pump, our thinking is to see if the misfires are on the same cylinders next time or if it’s as random as it seems._________________991.1 C2, 986 Boxster S
Past pleasures: 997.1 GT3, 997.2 C4S Cab, 993 C2, 997.1 C2S, 996.1 C4

deMortLong Beach

Joined: 21 Mar 2015Posts: 6152Location: Brighton

Posted: Sun Nov 18, 2018 5:03 pm Post subject:

It could be injectors but i tend to go with what i see most of the time and by logic ..

You would have to have 3 injectors blocked / damaged or have a feed problem .. always possible though .. some things i come across and i would never have guessed at the fault in a million years .

Nothing wrong with useing fuel cleaner and a good call .

Also you had already mentioned injectors so i didnt need to

Fuel pump is possible but i would like to see different cylinder misfires the next time to lean towards that .. also its more common to have a high rev lack of power as the pump never really delivers quite enough pressure .

I doubt you will hear it prime.

I think your car is too new to have a fuel filter but always best to make sure it hasnt ._________________.

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